1. Field of the Invention
The present invention relates to a communication-controlling apparatus and a control method thereof, and an image-capturing apparatus. More particularly, the invention relates to a communication-controlling apparatus that transfer image data and a control method thereof, and an image-capturing apparatus.
2. Description of the Related Art
Conventionally, in digital cameras, DCF (Design rule for Camera File system) is generally adopted as a file system for use when recording image data acquired by photographing. According to DCF, it is possible to embed data of a thumbnail image that is a reduced image corresponding to the image in question in a file (hereunder, referred to as “JPEG file”) that stores JPEG data obtained by applying compression encoding according to the JPEG standard to image data acquired by photographing.
Development is also proceeding with respect to digital cameras with a wireless communication function that can transmit image data obtained by photographing directly to a server or the like from the digital camera by wireless communication. By using such kind of digital camera with a wireless communication function, a user can efficiently utilize the recording capacity of a recording medium attached to the digital camera. However, when transmitting image data by wireless communication using a digital camera with a wireless communication function, if the data size of image data is oversized with respect to the communication speed, a long time is required to complete the communication.
In this regard, Japanese Patent Laid-Open No. 2004-341586 discloses technology that records both image data of a normal size that is acquired by photographing a subject and image data of a smaller size that is generated based on the image data in question on a recording medium, and transmits only the small-size image data to a server. By using the technology disclosed in Japanese Patent Laid-Open No. 2004-341586, a communication time required for transmitting image data can be shortened.
Amidst these demands with respect to image transmission, a memory card with a communication function for specialized use with digital cameras has been developed. The memory card is called an “Eye-Fi card” (registered trademark). This memory card with a communication function integrates a communication function by use of a wireless LAN into a memory card that has a non-volatile semiconductor memory. When this memory card is attached as the recording medium of a digital camera, it is possible to automatically transmit recorded image data to a predetermined destination.
However, since a feature of this memory card with a communication function is that the card transmits all JPEG files that exist inside a folder conforming to DCF, there is the following problem. That is, according to this memory card with a communication function, image data is transmitted irrespective of the data size of the image data to be transmitted. Consequently, even image files that have a large data size are objects of transmission, and in some cases a great deal of time is required to complete transmission.